In the last days (that is the whole period of time following Jesus ascension) people will not endure sound doctrine, but having itching ears, will seek out teachers who tell them things they like to hear. (VERY loosely paraphrased by my memory!) This is not an intellectual thing. Following Jesus is a matter of the heart and of the spirit.
No one who truly has a heart for the knowledge of God will ever be permanently deceived by a lie, so while it is important to be ready to explain the true gospel to those who may be in deception and who are willing to hear, it is not a matter of great concern to me. As a child does not (and should not) concern himself with his parents' financial matters, so we need not concern ourselves with God's work. When He has a task for us, He'll let us know. Our primary concern is learning to know Him.